The main way I completed my goals was to practice my goals at home like for handwriting I wrote in a diary or a book about what I did that day. And for my other goals like my maths I grabbed some maths sheets from the clipboard that the teacher set out for my maths group to help us achieve our maths goals.
The other way I completed my maths goals was to go on http://www.mathletics.co.nz/ or http://www.studyladder.co.nz/ they have maths activities that
helped me get better at my maths. My other goal was to get better at decimals so i used this website http://www.math.com/homeworkhelp/HotSubjects_decimals.html it helped me to get my goal of decimals it helped me to understand them and to learn that they arent scary. Also what helped me achieve my goals was to ask my parents what and how to use them and what do they do, Because asking someone whos older than you (and way smarter than you) will help you understand specific things or learn more about the things youre asking about.
another way that it can help you is to use a calculater or something to use the internet or youtube to watch videos to help you.
This is what we are learning in science
Effects on Plants
Physiological and developmental processes of plants are affected by UVB radiation, even by the amount of UVB in present-day sunlight. Despite mechanisms to reduce or repair these effects and a limited ability to adapt to increased levels of UVB, plant growth can be directly affected by UVB radiation. Indirect changes caused by UVB (such as changes in plant form, how nutrients are distributed within the plant, timing of developmental phases and secondary metabolism) may be equally, or sometimes more, important than damaging effects of UVB. These changes can have important implications for plant competitive balance, herbivory, plant diseases, and biogeochemical cycles.
Effects on Marine Ecosystems
Phytoplankton form the foundation of aquatic food webs. Phytoplankton productivity is limited to the euphotic zone, the upper layer of the water column in which there is sufficient sunlight to support net productivity. The position of the organisms in the euphotic zone is influenced by the action of wind and waves. In addition, many phytoplankton are capable of active movements that enhance their productivity and, therefore, their survival. Exposure to solar UVB radiation has been shown to affect both orientation mechanisms and motility in phytoplankton, resulting in reduced survival rates for these organisms. Scientists have demonstrated a direct reduction in phytoplankton production due to ozone depletion-related increases in UVB. One study has indicated a 6-12% reduction in the marginal ice zone. Solar UVB radiation has been found to cause damage to early developmental stages of fish, shrimp, crab, amphibians and other animals. The most severe effects are decreased reproductive capacity and impaired larval development. Even at current levels, solar UVB radiation is a limiting factor, and small increases in UVB exposure could result in significant reduction in the size of the population of animals that eat these smaller creatures.
Effects on Biogeochemical Cycles
Increases in solar UV radiation could affect terrestrial and aquatic biogeochemical cycles, thus altering both sources and sinks of greenhouse and chemically-important trace gases e.g., carbon dioxide (CO2), carbon monoxide (CO), carbonyl sulfide (COS) and possibly other gases, including ozone. These potential changes would contribute to biosphere-atmosphere feedbacks that attenuate or reinforce the atmospheric buildup of these gases.
Effects on Materials
Synthetic polymers, naturally occurring biopolymers, as well as some other materials of commercial interest are adversely affected by solar UV radiation. Today's materials are somewhat protected from UVB by special additives. Therefore, any increase in solar UVB levels will therefore accelerate their breakdown, limiting the length of time for which they are useful outdoors.
Health and Environmental Effects of Ozone Layer Depletion
The Connection Between Ozone Layer Depletion and UVB Radiation
Reductions in stratospheric ozone levels will lead to higher levels of __UVB__ reaching the Earth's surface. The sun's output of UVB does not change; rather, less ozone means less protection, and hence more UVB reaches the Earth. Studies have shown that in the Antarctic, the amount of UVB measured at the surface can double during the annual ozone hole. Another study confirmed the relationship between reduced ozone and increased UVB levels in Canada during the past several years.
Effects on Human Health
Laboratory and epidemiological studies demonstrate that UVB causes nonmelanoma skin cancer and plays a major role in malignant melanoma development. In addition, UVB has been linked to cataracts -- a clouding of the eye’s lens. All sunlight contains some UVB, even with normal stratospheric ozone levels. It is always important to __protect your skin and eyes from the sun__. Ozone layer depletion increases the amount of UVB and the risk of health effects. EPA uses the Atmospheric and Health Effects Framework (AHEF) model, developed in the mid 1980s, to estimate the health benefits of stronger ozone layer protection policies under the __Montreal Protocol__. EPA estimates avoided skin cancer cases, skin cancer deaths, and cataract cases in the United States.
This 2006 peer-reviewed report describes the analytical and empirical methodologies used by the AHEF model.
Effects on Plants
Physiological and developmental processes of plants are affected by UVB radiation, even by the amount of UVB in present-day sunlight. Despite mechanisms to reduce or repair these effects and a limited ability to adapt to increased levels of UVB, plant growth can be directly affected by UVB radiation. Indirect changes caused by UVB (such as changes in plant form, how nutrients are distributed within the plant, timing of developmental phases and secondary metabolism) may be equally, or sometimes more, important than damaging effects of UVB. These changes can have important implications for plant competitive balance, herbivory, plant diseases, and biogeochemical cycles.
Effects on Marine Ecosystems
Phytoplankton form the foundation of aquatic food webs. Phytoplankton productivity is limited to the euphotic zone, the upper layer of the water column in which there is sufficient sunlight to support net productivity. The position of the organisms in the euphotic zone is influenced by the action of wind and waves. In addition, many phytoplankton are capable of active movements that enhance their productivity and, therefore, their survival. Ex Physiological by iain aj help me
Science: Ozone Basics Ozone is very rare in our atmosphere, averaging about three molecules of ozone for every 10 million air molecules. In spite of this small amount, ozone plays a vital role in the atmosphere. In the information below, we present "the basics" about this important component of the Earth's atmosphere.
Where is ozone found in the atmosphere? Ozone is mainly found in two regions of the Earth's atmosphere. Most ozone (about 90%) resides in a layer that begins between 6 and 10 miles (10 and 17 kilometers) above the Earth's surface and extends up to about 30 miles (50 kilometers). This region of the atmosphere is called the stratosphere. The ozone in this region is commonly known as the ozone layer. The remaining ozone is in the lower region of the atmosphere, which is commonly called the troposphere. The figure (above) shows an example of how ozone is distributed in the atmosphere. What roles does ozone play in the atmosphere and how are humans affected? The ozone molecules in the upper atmosphere (stratosphere) and the lower atmosphere (troposphere) are chemically identical, because they all consist of three oxygen atoms and have the chemical formula O3. However, they have very different roles in the atmosphere and very different effects on humans and other living beings. Stratospheric ozone (sometimes referred to as "good ozone") plays a beneficial role by absorbing most of the biologically damaging ultraviolet sunlight (called UV-B), allowing only a small amount to reach the Earth's surface. The absorption of ultraviolet radiation by ozone creates a source of heat, which actually forms the stratosphere itself (a region in which the temperature rises as one goes to higher altitudes). Ozone thus plays a key role in the temperature structure of the Earth's atmosphere. Without the filtering action of the ozone layer, more of the Sun's UV-B radiation would penetrate the atmosphere and would reach the Earth's surface. Many experimental studies of plants and animals and clinical studies of humans have shown the harmful effects of excessive exposure to UV-B radiation. At the Earth's surface, ozone comes into direct contact with life-forms and displays its destructive side (hence, it is often called "bad ozone"). Because ozone reacts strongly with other molecules, high levels of ozone are toxic to living systems. Several studies have documented the harmful effects of ozone on crop production, forest growth, and human health. The substantial negative effects of surface-level tropospheric ozone from this direct toxicity contrast with the benefits of the additional filtering of UV-B radiation that it provides. What are the environmental issues associated with ozone? The dual role of ozone leads to two separate environmental issues. There is concern about increases in ozone in the troposphere. Near-surface ozone is a key component of photochemical "smog," a familiar problem in the atmosphere of many cities around the world. Higher amounts of surface-level ozone are increasingly being observed in rural areas as well. There is also widespread scientific and public interest and concern about losses of ozone in the stratosphere. Ground-based and satellite instruments have measured decreases in the amount of stratospheric ozone in our atmosphere. Over some parts of Antarctica, up to 60% of the total overhead amount of ozone (known as the column ozone) is depleted during Antarctic spring (September-November). This phenomenon is known as the Antarctic ozone hole. In the Arctic polar regions, similar processes occur that have also led to significant chemical depletion of the column ozone during late winter and spring in 7 out of the last 11 years. The ozone loss from January through late March has been typically 20-25%, and shorter-period losses have been higher, depending on the meteorological conditions encountered in the Arctic stratosphere. Smaller, but still significant, stratospheric decreases have been seen at other, more-populated regions of the Earth. Increases in surface UV-B radiation have been observed in association with local decreases in stratospheric ozone, from both ground-based and satellite-borne instruments. What human activities affect upper-atmospheric ozone (the stratospheric ozone layer)? The scientific evidence, accumulated over more than two decades of study by the international research community, has shown that human-produced chemicals are responsible for the observed depletions of the ozone layer. The ozone-depleting compounds contain various combinations of the chemical elements chlorine, fluorine, bromine, carbon, and hydrogen and are often described by the general term halocarbons. The compounds that contain only chlorine, fluorine, and carbon are called chlorofluorocarbons, usually abbreviated as CFCs. CFCs, carbon tetrachloride, and methyl chloroform are important human-produced ozone-depleting gases that have been used in many applications including refrigeration, air conditioning, foam blowing, cleaning of electronics components, and as solvents. Another important group of human-produced halocarbons is the halons, which contain carbon, bromine, fluorine, and (in some cases) chlorine and have been mainly used as fire extinguishants. What actions have been taken to protect the ozone layer? Through an international agreement known as the Montreal Protocol on Substances that Deplete the Ozone Layer, governments have decided to eventually discontinue production of CFCs, halons, carbon tetrachloride, and methyl chloroform (except for a few special uses), and industry has developed more "ozone-friendly" substitutes. All other things being equal, and with adherence to the international agreements, the ozone layer is expected to recover over the next 50 years or so. * Text and figure are adapted from the Introduction to "Frequently Asked Questions" of the World Meteorological Organization/United Nations Environment Programme report, Scientific Assessment of Ozone Depletion: 1998 (WMO Global Ozone Research and Monitoring Project-Report No. 44, Geneva, 1999).
The easiest way to come to grips with the Ozone Layer is to imagine the earth's atmosphere as a layered cake.Our atmosphere is split into a number of layers, beginning with the "troposphere" which is where we all live. Above that is the "stratosphere", which is where most planes fly and in there, you'll also find the planet's Ozone Layer. (Ozone actually exists to some degree in all of the layers but most of it - thought to be around 90 per cent - is produced naturally in the stratosphere.) Basically, the Ozone Layer is a planetary sunscreen and it plays a vital part in protecting us from most of the sun's harmful radiation. Scientists believe that without it, mankind and most animals on Earth would die. Without its protection, we would quickly suffer intense radiation burns unless we found some way to shield ourselves such as by wearing special clothing or living underground. Even then, a lot of the plant life that humans and animals depend on would die out, making food sources extremely scarce.
What Exactly is Ozone?
Ozone itself is a type of oxygen but unlike the oxygen that we need to breathe, it is a poisonous gas. So, although ozone in the stratosphere is good and performs a vital function, ozone at ground level is bad. It is the main ingredient of today's city smog and irritates conditions like asthma, bronchitis and lung disease. The oxygen we breathe is made up of two oxygen atoms but ozone molecules have three and unlike oxygen, which is odourless, ozone has a very strong odour (its name comes from the Greek word meaning "to smell"). People often refer to the planet's Ozone Layer as a protective shield but in reality it acts more like a sieve or a web because although it traps harmful radiation, it still allows heat from the sun to reach Earth.
titude sickness—also known as acute mountain sickness (AMS), altitude illness, hypobaropathy, "the altitude bends", or soroche—is a pathologicaleffect of high altitude on humans, caused by acute exposure to lowpartial pressure of oxygenathigh altitude. It commonly occurs above 2,400 metres (8,000 feet).[1][2]It presents as a collection ofnonspecific symptoms, acquired at high altitude or in low air pressure, resembling a case of "flu, carbon monoxide poisoning, or a hangover".[3]It is hard to determine who will be affected by altitude sickness, as there are no specific factors that correlate with a susceptibility to altitude sickness. However, most people can ascend to 2,400 metres (8,000 ft) without difficulty. Acute mountain sickness can progress tohigh altitude pulmonary edema(HAPE) orhigh altitude cerebral edema(HACE), which are potentially fatal.[2][4] Chronic mountain sickness, also known as Monge's disease, is a different condition that only occurs after very prolonged exposure to high altitude.[5]
The available amount of oxygen to sustain mental and physical alertness decreases with altitude. Available oxygen drops as the air density itself, the number of molecules (of both oxygen and nitrogen) per given volume, drops as altitude increases. However, the percentage of oxygen in air, at 21%, remains almost unchanged up to 21,000 metres (69,000 ft).[6]TheRMS velocitiesof diatomic nitrogen and oxygen are very similar and thus no change occurs in the ratio of oxygen to nitrogen. Dehydrationdue to the higher rate of water vapor lost from the lungs at higher altitudes may contribute to the symptoms of altitude sickness.[7] The rate of ascent, altitude attained, amount of physical activity at high altitude, as well as individual susceptibility, are contributing factors to the onset and severity of high-altitude illness. Altitude sickness usually occurs following a rapid ascent and can usually be prevented by ascending slowly.[4]In most of these cases, the symptoms are temporary and usually abate as altitude acclimatization occurs. However, in extreme cases, altitude sickness can be fatal.
how to avoid it
Ascending slowly is the best way to avoid altitude sickness.[4] Avoiding strenuous activity such as skiing, hiking, etc. in the first 24 hours at high altitude reduces the symptoms of AMS. Alcohol and sleeping pills are respiratory depressants, and thus slows down the acclimatization process and should be avoided. Alcohol also tends to cause dehydration and exacerbates AMS. Thus, avoiding alcohol consumption in the first 24–48 hours at a higher altitude is optimal.
other methods
increased water intake may also help in acclimatization[26] to replace the fluids lost through heavier breathing in the thin, dry air found at altitude, although consuming excessive quantities ("over-hydration") has no benefits and may cause dangerous hyponatremia. It’s a good idea to limit alcohol intake the first day or so at higher elevation as well. Oxygen from gas bottles or liquid containers can be applied directly via a nasal cannula or mask. Oxygen concentrators based upon pressure swing adsorption (PSA), VSA, or vacuum-pressure swing adsorption (VPSA) can be used to generate the oxygen if electricity is available. Stationary oxygen concentrators typically use PSA technology, which has performance degradations at the lower barometric pressures at high altitudes. One way to compensate for the performance degradation is to utilize a concentrator with more flow capacity. There are also portable oxygen concentrators that can be used on vehicular DC power or on internal batteries, and at least one system commercially available measures and compensates for the altitude effect on its performance up to 4,000 meters (13,000 ft). The application of high-purity oxygen from one of these methods increases the partial pressure of oxygen by raising the FiO2 (fraction of inspired oxygen).
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Electronics day
I enjoyed doing Electronics yesterday I loved wiring up the Christmas tree and the speakers. When we were soldering we heard a few yelps of pain because we were burning our selfs (not on purpose) The part I really enjoyed was seeing my Christmas tree finished because I knew that all of my hard work had payed off. I loved hearing my Christmas tree play the tunes and flash its lights. I felt very good about myself. I really want to take it home now. I love my Christmas tree so much! the wiring up was easy when you got the hang of it and the soldering was great fun to I would really like to be and engineer and make this kind of stuff. I liked using the yellow thing to see the amount of ONES? ( they have all the power ). It got quite confusing half way through the making of the Christmas tree because there was harder stuff to do. I enjoyed making them and would love to use all that stuff again soon. :) :)
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The bake sale!.
I think the bake sale went very well the food tasted very good I like the lemon Tarts. They are very nice Jacob made the lemon Tarts.
I thought that the lemon slice was the best because of the sweetness it tasted amazing like lemon meringue
.
The lemonade was very nice to, I did not help make anything but I liked how they all worked together to make all the great tasting food and i hope my group can do the same.
Capital letters ........Iain ..... PLEASE use capital letters when you write "I" and also for names ....."Jacob". Spelling = tasted sweetness meringue Food is more than "nice" .... please use vocabulary that is a bit more descriptive ...." They were tangy"
When to use a full stop or comma ....
download.jpg
THIS IS THE FRENCH FLAG!
TERM 4
1 to listen to the teacher more
2 get better at linking
3 to go on studyladder more
this is a comon factor photo that helped me alot to understand it
Yesterday i found out that on thursday friday and saturday leaving on sunday im going to my birth familys place which i think is really awesome because i have not seen them for ages......!!!!!
Science BRIDGES!
in science we are doing brigdes and my group which is Caleb Jacob Tom and I are doing a draw bridge
specificity we are doing the London draw bridge which is a very interesting design it is built by the English scientists and
this design has two weights at both sides close to the middle and then when the bridge needs to go up for instints a cruise liner is coming under or past the bridge the cars stop the man in the tower presses the buttons to lift up the bridge and those two weights on both sides will be lowered as the main part of the bridge is lifted up. The bridge islifted up by some weights yes but how does the bridge get lifted and lowered its not just the weights that are doing everthing also there are axls with are liked sticks or poles in this state with another hollow pole that the other pole goes into to creater an axl the axls are attached to the bridge as the poles are attached to the weights so the weights don't do all the work the axls are also in cars to control the wheels when they turn around. these are the axls here. thankyou for reading this and i hope you will enjoy our bridge
BY iain three Adgetives that best describes your....... .self .friend .teacher .parent
Once my family went to Australia we went to the Gold coast in Australia we went to movie world inside the first thing that you saw was big rollar costers. we saw lots and lots of rides and we went for a very long trip to the bumper cars. i liked the bumper cars because they were allowed to bump into each other it was fun. i also liked going to the big drop it was very scary for me because i never done it before.i also went to a racing car place and we went ot the big scooby doo rollar coaster me and georgia were crying after cause it was scary. i did not like it and then i was sposed to go on another one called the raod runner and guess what i said no thankyou mum not after the other one. i did not like the scooby doo one it was scary.
spelling words for this week 1.disaster 2.earthquake 3.shocked 4.leaped 5.quick
I recommend this book because it is very interesting this is what it is about: The Victoria cross the biggest military
award for bravery in the commonwealth, and has been won by some of our best and bravest.
Here are the stories of the 26 men who won the VC in the first world war
=
=
my spelling words for term 2!!!
earthquake
February
quake
deaths
November
TERM 2
videos of the week
goals my goals
1st is that i have to learn my decimals 2nd is that i will get neater at writing 3rd is that i will get awesome at times table
thank you for coming to help with camp thak you for helping me pack if it wasnt for you
i would of gone up the hill dead
thank you for coming up to Huxley lodge it was awesome you were awesome when you came to help with the pe
if it wasnt for you i would still be up that rock
i hope you will come next year
from iain
ps; how did you run up the tramp track!!!!!!
miss meclenans fomous meat loaf all my family love!!!!!!!
ians wiki is awesome who would like me to ivite them
MY MATHS GOAL IS THAT I WOULD GET BETTER AT MATHS BY THE END OF THE YEAR!!!!!
thats girl is my old aupair
camp bunk rooms
in the night when we were playing truth or dare in the boys cabin some of the boys were seeing a so called monster which was not real and was very funny. then in the middle of the night jacob asked me if i could go to the bathroom with him because he was to scared to go by himself so i said yes. then we got back and went to sleep i woke up baning my head and it hurt.and then i walked down the stairs and up and on the way up i smashed to big toe and got motion sickness i was very dosey. because blood was going fast out of my body.i loved staying in the bunks but tidying them up was adifferent story
awesome stories
M1 Camp Recount
We got there in the vans and when we got there got our staff and went up the hill,
tramping up the hill is where hared,
I got skak in a tree,
tents are hard to put up,
I loved sleep in my own bed,
in own house instead of a tent,
sleep in the tent and when I woke up I had sun skream muska on my face,
we got up we went down the hill one time again, before we went and sowe 6 little kea’s,
when we got down we went to the vans to the lag,
when we got there we got a little nap,
In my own bed,
with my friends ,
propyl sleep night,
cabin beds soooo soft , bedrolls not so soft than I thot,
cabin showers has cold waters,
see a thing at night,
can not sleep at all but sleep at the end
but it is not so bad.
By A.J. and iain
when i cracked my funny bone
when i went to the church hall i was playing on bars and jumping over them when that meeting to finish i was going to jump over the bar to go to the car and then.SMACK! i was lying on the ground in lots of pain it really hurt.Mum and dad were there looking at me and said i bet if you didnt tell us to watch you jump over the bar it wouldnt of fail to lift me.then in the night i fell out of bed and it hurt.!!!!. when i went to australia when we got to australia it was 5:30 pm we left at 4:08am and we were all tired but we had to be at check in at 8:00 am so we had hours to spend we were all looking forword to getting to australia in one piece so when we got on the plane i brought an jet star i pad i started to play NOVA it was an awesome game i loved i played that for an hour and a half and then for the next 2 and a half hours i watched the hobbit the desolation of smaug it was awesome
camp my recount
my favorite thing about camp was when we saw the so called monster.It was so funny when the morning came. Because all the boys were trying to figure it out and me and kian were laughing and laughing it was so funny.BUT when they saw the so called monster i was a bit scared it was scary at first.Then me and kian went to the toliet and laughed and laughed.
This is what we are learning in class
Science: Ozone Basics Ozone is very rare in our atmosphere, averaging about three molecules of ozone for every 10 million air molecules. In spite of this small amount, ozone plays a vital role in the atmosphere. In the information below, we present "the basics" about this important component of the Earth's atmosphere.
Where is ozone found in the atmosphere? Ozone is mainly found in two regions of the Earth's atmosphere. Most ozone (about 90%) resides in a layer that begins between 6 and 10 miles (10 and 17 kilometers) above the Earth's surface and extends up to about 30 miles (50 kilometers). This region of the atmosphere is called the stratosphere. The ozone in this region is commonly known as the ozone layer. The remaining ozone is in the lower region of the atmosphere, which is commonly called the troposphere. The figure (above) shows an example of how ozone is distributed in the atmosphere. What roles does ozone play in the atmosphere and how are humans affected? The ozone molecules in the upper atmosphere (stratosphere) and the lower atmosphere (troposphere) are chemically identical, because they all consist of three oxygen atoms and have the chemical formula O3. However, they have very different roles in the atmosphere and very different effects on humans and other living beings. Stratospheric ozone (sometimes referred to as "good ozone") plays a beneficial role by absorbing most of the biologically damaging ultraviolet sunlight (called UV-B), allowing only a small amount to reach the Earth's surface. The absorption of ultraviolet radiation by ozone creates a source of heat, which actually forms the stratosphere itself (a region in which the temperature rises as one goes to higher altitudes). Ozone thus plays a key role in the temperature structure of the Earth's atmosphere. Without the filtering action of the ozone layer, more of the Sun's UV-B radiation would penetrate the atmosphere and would reach the Earth's surface. Many experimental studies of plants and animals and clinical studies of humans have shown the harmful effects of excessive exposure to UV-B radiation. At the Earth's surface, ozone comes into direct contact with life-forms and displays its destructive side (hence, it is often called "bad ozone"). Because ozone reacts strongly with other molecules, high levels of ozone are toxic to living systems. Several studies have documented the harmful effects of ozone on crop production, forest growth, and human health. The substantial negative effects of surface-level tropospheric ozone from this direct toxicity contrast with the benefits of the additional filtering of UV-B radiation that it provides. What are the environmental issues associated with ozone? The dual role of ozone leads to two separate environmental issues. There is concern about increases in ozone in the troposphere. Near-surface ozone is a key component of photochemical "smog," a familiar problem in the atmosphere of many cities around the world. Higher amounts of surface-level ozone are increasingly being observed in rural areas as well. There is also widespread scientific and public interest and concern about losses of ozone in the stratosphere. Ground-based and satellite instruments have measured decreases in the amount of stratospheric ozone in our atmosphere. Over some parts of Antarctica, up to 60% of the total overhead amount of ozone (known as the column ozone) is depleted during Antarctic spring (September-November). This phenomenon is known as the Antarctic ozone hole. In the Arctic polar regions, similar processes occur that have also led to significant chemical depletion of the column ozone during late winter and spring in 7 out of the last 11 years. The ozone loss from January through late March has been typically 20-25%, and shorter-period losses have been higher, depending on the meteorological conditions encountered in the Arctic stratosphere. Smaller, but still significant, stratospheric decreases have been seen at other, more-populated regions of the Earth. Increases in surface UV-B radiation have been observed in association with local decreases in stratospheric ozone, from both ground-based and satellite-borne instruments. What human activities affect upper-atmospheric ozone (the stratospheric ozone layer)? The scientific evidence, accumulated over more than two decades of study by the international research community, has shown that human-produced chemicals are responsible for the observed depletions of the ozone layer. The ozone-depleting compounds contain various combinations of the chemical elements chlorine, fluorine, bromine, carbon, and hydrogen and are often described by the general term halocarbons. The compounds that contain only chlorine, fluorine, and carbon are called chlorofluorocarbons, usually abbreviated as CFCs. CFCs, carbon tetrachloride, and methyl chloroform are important human-produced ozone-depleting gases that have been used in many applications including refrigeration, air conditioning, foam blowing, cleaning of electronics components, and as solvents. Another important group of human-produced halocarbons is the halons, which contain carbon, bromine, fluorine, and (in some cases) chlorine and have been mainly used as fire extinguishants. What actions have been taken to protect the ozone layer? Through an international agreement known as the Montreal Protocol on Substances that Deplete the Ozone Layer, governments have decided to eventually discontinue production of CFCs, halons, carbon tetrachloride, and methyl chloroform (except for a few special uses), and industry has developed more "ozone-friendly" substitutes. All other things being equal, and with adherence to the international agreements, the ozone layer is expected to recover over the next 50 years or so. * Text and figure are adapted from the Introduction to "Frequently Asked Questions" of the World Meteorological Organization/United Nations Environment Programme report, Scientific Assessment of Ozone Depletion: 1998 (WMO Global Ozone Research and Monitoring Project-Report No. 44, Geneva, 1999).
Iains page!
Foods
i am doing
mauritius
sowing for 2015 tech
I am going to try and make an stag pillow
My goals that i have achieved//
The main way I completed my goals was to practice my goals at home like for handwriting I wrote in a diary or a book about what I did that day. And for my other goals like my maths I grabbed some maths sheets from the clipboard that the teacher set out for my maths group to help us achieve our maths goals.
The other way I completed my maths goals was to go on http://www.mathletics.co.nz/ or http://www.studyladder.co.nz/ they have maths activities that
helped me get better at my maths. My other goal was to get better at decimals so i used this website http://www.math.com/homeworkhelp/HotSubjects_decimals.html it helped me to get my goal of decimals it helped me to understand them and to learn that they arent scary. Also what helped me achieve my goals was to ask my parents what and how to use them and what do they do, Because asking someone whos older than you (and way smarter than you) will help you understand specific things or learn more about the things youre asking about.
another way that it can help you is to use a calculater or something to use the internet or youtube to watch videos to help you.
This is what we are learning in science
Effects on Plants
Physiological and developmental processes of plants are affected by UVB radiation, even by the amount of UVB in present-day sunlight. Despite mechanisms to reduce or repair these effects and a limited ability to adapt to increased levels of UVB, plant growth can be directly affected by UVB radiation.Indirect changes caused by UVB (such as changes in plant form, how nutrients are distributed within the plant, timing of developmental phases and secondary metabolism) may be equally, or sometimes more, important than damaging effects of UVB. These changes can have important implications for plant competitive balance, herbivory, plant diseases, and biogeochemical cycles.
Effects on Marine Ecosystems
Phytoplankton form the foundation of aquatic food webs. Phytoplankton productivity is limited to the euphotic zone, the upper layer of the water column in which there is sufficient sunlight to support net productivity. The position of the organisms in the euphotic zone is influenced by the action of wind and waves. In addition, many phytoplankton are capable of active movements that enhance their productivity and, therefore, their survival. Exposure to solar UVB radiation has been shown to affect both orientation mechanisms and motility in phytoplankton, resulting in reduced survival rates for these organisms. Scientists have demonstrated a direct reduction in phytoplankton production due to ozone depletion-related increases in UVB. One study has indicated a 6-12% reduction in the marginal ice zone.Solar UVB radiation has been found to cause damage to early developmental stages of fish, shrimp, crab, amphibians and other animals. The most severe effects are decreased reproductive capacity and impaired larval development. Even at current levels, solar UVB radiation is a limiting factor, and small increases in UVB exposure could result in significant reduction in the size of the population of animals that eat these smaller creatures.
Effects on Biogeochemical Cycles
Increases in solar UV radiation could affect terrestrial and aquatic biogeochemical cycles, thus altering both sources and sinks of greenhouse and chemically-important trace gases e.g., carbon dioxide (CO2), carbon monoxide (CO), carbonyl sulfide (COS) and possibly other gases, including ozone. These potential changes would contribute to biosphere-atmosphere feedbacks that attenuate or reinforce the atmospheric buildup of these gases.Effects on Materials
Synthetic polymers, naturally occurring biopolymers, as well as some other materials of commercial interest are adversely affected by solar UV radiation. Today's materials are somewhat protected from UVB by special additives. Therefore, any increase in solar UVB levels will therefore accelerate their breakdown, limiting the length of time for which they are useful outdoors.Health and Environmental Effects of Ozone Layer Depletion
The Connection Between Ozone Layer Depletion and UVB Radiation
Reductions in stratospheric ozone levels will lead to higher levels of __UVB__ reaching the Earth's surface. The sun's output of UVB does not change; rather, less ozone means less protection, and hence more UVB reaches the Earth. Studies have shown that in the Antarctic, the amount of UVB measured at the surface can double during the annual ozone hole. Another study confirmed the relationship between reduced ozone and increased UVB levels in Canada during the past several years.Effects on Human Health
Laboratory and epidemiological studies demonstrate that UVB causes nonmelanoma skin cancer and plays a major role in malignant melanoma development. In addition, UVB has been linked to cataracts -- a clouding of the eye’s lens. All sunlight contains some UVB, even with normal stratospheric ozone levels. It is always important to __protect your skin and eyes from the sun__. Ozone layer depletion increases the amount of UVB and the risk of health effects.EPA uses the Atmospheric and Health Effects Framework (AHEF) model, developed in the mid 1980s, to estimate the health benefits of stronger ozone layer protection policies under the __Montreal Protocol__. EPA estimates avoided skin cancer cases, skin cancer deaths, and cataract cases in the United States.
Effects on Plants
Physiological and developmental processes of plants are affected by UVB radiation, even by the amount of UVB in present-day sunlight. Despite mechanisms to reduce or repair these effects and a limited ability to adapt to increased levels of UVB, plant growth can be directly affected by UVB radiation.Indirect changes caused by UVB (such as changes in plant form, how nutrients are distributed within the plant, timing of developmental phases and secondary metabolism) may be equally, or sometimes more, important than damaging effects of UVB. These changes can have important implications for plant competitive balance, herbivory, plant diseases, and biogeochemical cycles.
Effects on Marine Ecosystems
Phytoplankton form the foundation of aquatic food webs. Phytoplankton productivity is limited to the euphotic zone, the upper layer of the water column in which there is sufficient sunlight to support net productivity. The position of the organisms in the euphotic zone is influenced by the action of wind and waves. In addition, many phytoplankton are capable of active movements that enhance their productivity and, therefore, their survival. ExPhysiological
by iain
aj help me
||
Last updated on 24 November 2013 by ghoori@twizel.school.nz
Ozone is very rare in our atmosphere, averaging about three molecules of ozone for every 10 million air molecules. In spite of this small amount, ozone plays a vital role in the atmosphere. In the information below, we present "the basics" about this important component of the Earth's atmosphere.
__Click here for larger image__
Ozone is mainly found in two regions of the Earth's atmosphere. Most ozone (about 90%) resides in a layer that begins between 6 and 10 miles (10 and 17 kilometers) above the Earth's surface and extends up to about 30 miles (50 kilometers). This region of the atmosphere is called the stratosphere. The ozone in this region is commonly known as the ozone layer. The remaining ozone is in the lower region of the atmosphere, which is commonly called the troposphere. The figure (above) shows an example of how ozone is distributed in the atmosphere.
What roles does ozone play in the atmosphere and how are humans affected?
The ozone molecules in the upper atmosphere (stratosphere) and the lower atmosphere (troposphere) are chemically identical, because they all consist of three oxygen atoms and have the chemical formula O3. However, they have very different roles in the atmosphere and very different effects on humans and other living beings. Stratospheric ozone (sometimes referred to as "good ozone") plays a beneficial role by absorbing most of the biologically damaging ultraviolet sunlight (called UV-B), allowing only a small amount to reach the Earth's surface. The absorption of ultraviolet radiation by ozone creates a source of heat, which actually forms the stratosphere itself (a region in which the temperature rises as one goes to higher altitudes). Ozone thus plays a key role in the temperature structure of the Earth's atmosphere. Without the filtering action of the ozone layer, more of the Sun's UV-B radiation would penetrate the atmosphere and would reach the Earth's surface. Many experimental studies of plants and animals and clinical studies of humans have shown the harmful effects of excessive exposure to UV-B radiation.
At the Earth's surface, ozone comes into direct contact with life-forms and displays its destructive side (hence, it is often called "bad ozone"). Because ozone reacts strongly with other molecules, high levels of ozone are toxic to living systems. Several studies have documented the harmful effects of ozone on crop production, forest growth, and human health. The substantial negative effects of surface-level tropospheric ozone from this direct toxicity contrast with the benefits of the additional filtering of UV-B radiation that it provides.
What are the environmental issues associated with ozone?
The dual role of ozone leads to two separate environmental issues. There is concern about increases in ozone in the troposphere. Near-surface ozone is a key component of photochemical "smog," a familiar problem in the atmosphere of many cities around the world. Higher amounts of surface-level ozone are increasingly being observed in rural areas as well.
There is also widespread scientific and public interest and concern about losses of ozone in the stratosphere. Ground-based and satellite instruments have measured decreases in the amount of stratospheric ozone in our atmosphere. Over some parts of Antarctica, up to 60% of the total overhead amount of ozone (known as the column ozone) is depleted during Antarctic spring (September-November). This phenomenon is known as the Antarctic ozone hole. In the Arctic polar regions, similar processes occur that have also led to significant chemical depletion of the column ozone during late winter and spring in 7 out of the last 11 years. The ozone loss from January through late March has been typically 20-25%, and shorter-period losses have been higher, depending on the meteorological conditions encountered in the Arctic stratosphere. Smaller, but still significant, stratospheric decreases have been seen at other, more-populated regions of the Earth. Increases in surface UV-B radiation have been observed in association with local decreases in stratospheric ozone, from both ground-based and satellite-borne instruments.
What human activities affect upper-atmospheric ozone (the stratospheric ozone layer)?
The scientific evidence, accumulated over more than two decades of study by the international research community, has shown that human-produced chemicals are responsible for the observed depletions of the ozone layer. The ozone-depleting compounds contain various combinations of the chemical elements chlorine, fluorine, bromine, carbon, and hydrogen and are often described by the general term halocarbons. The compounds that contain only chlorine, fluorine, and carbon are called chlorofluorocarbons, usually abbreviated as CFCs. CFCs, carbon tetrachloride, and methyl chloroform are important human-produced ozone-depleting gases that have been used in many applications including refrigeration, air conditioning, foam blowing, cleaning of electronics components, and as solvents. Another important group of human-produced halocarbons is the halons, which contain carbon, bromine, fluorine, and (in some cases) chlorine and have been mainly used as fire extinguishants.
What actions have been taken to protect the ozone layer?
Through an international agreement known as the Montreal Protocol on Substances that Deplete the Ozone Layer, governments have decided to eventually discontinue production of CFCs, halons, carbon tetrachloride, and methyl chloroform (except for a few special uses), and industry has developed more "ozone-friendly" substitutes. All other things being equal, and with adherence to the international agreements, the ozone layer is expected to recover over the next 50 years or so.
* Text and figure are adapted from the Introduction to "Frequently Asked Questions" of the World Meteorological Organization/United Nations Environment Programme report, Scientific Assessment of Ozone Depletion: 1998 (WMO Global Ozone Research and Monitoring Project-Report No. 44, Geneva, 1999).
Above that is the "stratosphere", which is where most planes fly and in there, you'll also find the planet's Ozone Layer. (Ozone actually exists to some degree in all of the layers but most of it - thought to be around 90 per cent - is produced naturally in the stratosphere.)
Basically, the Ozone Layer is a planetary sunscreen and it plays a vital part in protecting us from most of the sun's harmful radiation. Scientists believe that without it, mankind and most animals on Earth would die.
Without its protection, we would quickly suffer intense radiation burns unless we found some way to shield ourselves such as by wearing special clothing or living underground. Even then, a lot of the plant life that humans and animals depend on would die out, making food sources extremely scarce.
What Exactly is Ozone?
Ozone itself is a type of oxygen but unlike the oxygen that we need to breathe, it is a poisonous gas. So, although ozone in the stratosphere is good and performs a vital function, ozone at ground level is bad. It is the main ingredient of today's city smog and irritates conditions like asthma, bronchitis and lung disease.The oxygen we breathe is made up of two oxygen atoms but ozone molecules have three and unlike oxygen, which is odourless, ozone has a very strong odour (its name comes from the Greek word meaning "to smell").
People often refer to the planet's Ozone Layer as a protective shield but in reality it acts more like a sieve or a web because although it traps harmful radiation, it still allows heat from the sun to reach Earth.
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http://www.ozonelayer.noaa.gov/science/basics.htm
Last updated on 20 March 2008 by iain ghoorah twizel
__ghoori@twizel.school.nz__
alltidued sickness
titude sickness—also known as acute mountain sickness (AMS), altitude illness, hypobaropathy, "the altitude bends", or soroche—is a pathological effect of high altitude on humans, caused by acute exposure to low partial pressure of oxygen at high altitude. It commonly occurs above 2,400 metres (8,000 feet).[1][2] It presents as a collection of nonspecific symptoms, acquired at high altitude or in low air pressure, resembling a case of "flu, carbon monoxide poisoning, or a hangover".[3] It is hard to determine who will be affected by altitude sickness, as there are no specific factors that correlate with a susceptibility to altitude sickness. However, most people can ascend to 2,400 metres (8,000 ft) without difficulty.
Acute mountain sickness can progress to high altitude pulmonary edema (HAPE) or high altitude cerebral edema(HACE), which are potentially fatal.[2][4]
Chronic mountain sickness, also known as Monge's disease, is a different condition that only occurs after very prolonged exposure to high altitude.[5]
The available amount of oxygen to sustain mental and physical alertness decreases with altitude. Available oxygen drops as the air density itself, the number of molecules (of both oxygen and nitrogen) per given volume, drops as altitude increases.
However, the percentage of oxygen in air, at 21%, remains almost unchanged up to 21,000 metres (69,000 ft).[6] The RMS velocities of diatomic nitrogen and oxygen are very similar and thus no change occurs in the ratio of oxygen to nitrogen.
Dehydration due to the higher rate of water vapor lost from the lungs at higher altitudes may contribute to the symptoms of altitude sickness.[7]
The rate of ascent, altitude attained, amount of physical activity at high altitude, as well as individual susceptibility, are contributing factors to the onset and severity of high-altitude illness.
Altitude sickness usually occurs following a rapid ascent and can usually be prevented by ascending slowly.[4] In most of these cases, the symptoms are temporary and usually abate as altitude acclimatization occurs. However, in extreme cases, altitude sickness can be fatal.
how to avoid it
Ascending slowly is the best way to avoid altitude sickness.[4] Avoiding strenuous activity such as skiing, hiking, etc. in the first 24 hours at high altitude reduces the symptoms of AMS. Alcohol and sleeping pills are respiratory depressants, and thus slows down the acclimatization process and should be avoided. Alcohol also tends to cause dehydration and exacerbates AMS. Thus, avoiding alcohol consumption in the first 24–48 hours at a higher altitude is optimal.
other methods
increased water intake may also help in acclimatization[26] to replace the fluids lost through heavier breathing in the thin, dry air found at altitude, although consuming excessive quantities ("over-hydration") has no benefits and may cause dangerous hyponatremia. It’s a good idea to limit alcohol intake the first day or so at higher elevation as well.
Oxygen from gas bottles or liquid containers can be applied directly via a nasal cannula or mask. Oxygen concentrators based upon pressure swing adsorption (PSA), VSA, or vacuum-pressure swing adsorption (VPSA) can be used to generate the oxygen if electricity is available. Stationary oxygen concentrators typically use PSA technology, which has performance degradations at the lower barometric pressures at high altitudes. One way to compensate for the performance degradation is to utilize a concentrator with more flow capacity. There are also portable oxygen concentrators that can be used on vehicular DC power or on internal batteries, and at least one system commercially available measures and compensates for the altitude effect on its performance up to 4,000 meters (13,000 ft). The application of high-purity oxygen from one of these methods increases the partial pressure of oxygen by raising the FiO2 (fraction of inspired oxygen).
I enjoyed doing Electronics yesterday I loved wiring up the Christmas tree and the speakers. When we were soldering we heard a few yelps of pain because we were burning our selfs (not on purpose) The part I really enjoyed was seeing my Christmas tree finished because I knew that all of my hard work had payed off. I loved hearing my Christmas tree play the tunes and flash its lights. I felt very good about myself. I really want to take it home now. I love my Christmas tree so much! the wiring up was easy when you got the hang of it and the soldering was great fun to I would really like to be and engineer and make this kind of stuff. I liked using the yellow thing to see the amount of ONES? ( they have all the power ). It got quite confusing half way through the making of the Christmas tree because there was harder stuff to do. I enjoyed making them and would love to use all that stuff again soon. :) :)
The bake sale!.
I think the bake sale went very well the food tasted very good I like the lemon Tarts. They are very nice Jacob made the lemon Tarts.
I thought that the lemon slice was the best because of the sweetness it tasted amazing like lemon meringue
.
The lemonade was very nice to, I did not help make anything but I liked how they all worked together to make all the great tasting food and i hope my group can do the same.
Capital letters ........Iain ..... PLEASE use capital letters when you write "I" and also for names ....."Jacob".
Spelling =
tasted
sweetness
meringue
Food is more than "nice" .... please use vocabulary that is a bit more descriptive ...." They were tangy"
When to use a full stop or comma ....
THIS IS THE FRENCH FLAG!
1 to listen to the teacher more
2 get better at linking
3 to go on studyladder more
this is a comon factor photo that helped me alot to understand it
http://www.mathsisfun.com/greatest-common-factor.html
http://www.mathsisfun.com/greatest-common-factor.html
COMMONFACTORS!!!
term4 17/10/14
in maths time we have been learinig about common factors it is an awesome and i love them now
this is what larnach castle in minecraft would look like
Yesterday i found out that on thursday friday and saturday leaving on sunday im going to my birth familys place which i think is really awesome because i have not seen them for ages......!!!!!
Science BRIDGES!
in science we are doing brigdes and my group which is Caleb Jacob Tom and I are doing a draw bridge
specificity we are doing the London draw bridge which is a very interesting design it is built by the English scientists and
this design has two weights at both sides close to the middle and then when the bridge needs to go up for instints a cruise liner is coming under or past the bridge the cars stop the man in the tower presses the buttons to lift up the bridge and those two weights on both sides will be lowered as the main part of the bridge is lifted up. The bridge islifted up by some weights yes but how does the bridge get lifted and lowered its not just the weights that are doing everthing also there are axls with are liked sticks or poles in this state with another hollow pole that the other pole goes into to creater an axl the axls are attached to the bridge as the poles are attached to the weights so the weights don't do all the work the axls are also in cars to control the wheels when they turn around.
BY iain
three Adgetives that best describes your.......
.self
.friend
.teacher
.parent
funny,determend,loyal
funny,caring,awesome
funny,cairng,loyal
determand,cool,trustworthy
his is were my DAD and most of my Family live / cousins / aunties and uncles!
my dad used to jump off of these trees!!!
HELLO everybody i have not be on forrr!! ages but now i am back and will be on alot more ....... here are some photos from my recent and old holidays
I Also Made A Collage
the book im reading is called conspericy 365
This book is about a teenage boy and he is on missions every week. In this book he wakes up from his previous mission in a Coffion
P.R.M Pike River Mine
Australia
Once my family went to Australia we went to the Gold coast in Australia we went to movie world inside the first thing that you saw was big rollar costers. we saw lots and lots of rides and we went for a very long trip to the bumper cars. i liked the bumper cars because they were allowed to bump into each other it was fun. i also liked going to the big drop it was very scary for me because i never done it before.i also went to a racing car place and we went ot the big scooby doo rollar coaster me and georgia were crying after cause it was scary. i did not like it and then i was sposed to go on another one called the raod runner and guess what i said no thankyou mum not after the other one. i did not like the scooby doo one it was scary.
spelling words for this week
1.disaster
2.earthquake
3.shocked
4.leaped
5.quick
adopt your own virtual pet!
MY GOALS FOR THIS WEEK
- to know my 9 times table off by heart
- to know my spelling off by heart
to get my new baybladeMY SPELLING WORD"S FOR THIS WEEK 22/05/14
I recommend this book because it is very interesting this is what it is about: The Victoria cross the biggest military
award for bravery in the commonwealth, and has been won by some of our best and bravest.
Here are the stories of the 26 men who won the VC in the first world war
=
=
my spelling words for term 2!!!
videos of the week
goals
my goals
1st is that i have to learn my decimals
2nd is that i will get neater at writing
3rd is that i will get awesome at times table
adopt your own virtual pet!
adopt your own virtual pet!
are you watching me PICS
adopt your own virtual pet!
adopt your own virtual pet!
my letter to mr frost
DEAR MR FROST
thank you for coming to help with camp thak you for helping me pack if it wasnt for you
i would of gone up the hill dead
thank you for coming up to Huxley lodge it was awesome you were awesome when you came to help with the pe
if it wasnt for you i would still be up that rock
i hope you will come next year
from iain
ps; how did you run up the tramp track!!!!!!
miss meclenans fomous meat loaf all my family love!!!!!!!
ians wiki is awesome who would like me to ivite them
email................ vandea@twizel.school.nz joshv@merin.school.nz
so i can invite u put your email here
stampy
)
my goals
- my goal is to get better at maths
- my second goal is to get better at litericy
the third goal is to get better at sportsnz army
MATHS WEBSITES AND VIDEOS!!!!!!
MY MATHS GOAL IS THAT I WOULD GET BETTER AT MATHS BY THE END OF THE YEAR!!!!!
camp bunk rooms
in the night when we were playing truth or dare in the boys cabin some of the boys were seeing a so called monster which was not real and was very funny. then in the middle of the night jacob asked me if i could go to the bathroom with him because he was to scared to go by himself so i said yes. then we got back and went to sleep i woke up baning my head and it hurt.and then i walked down the stairs and up and on the way up i smashed to big toe and got motion sickness
i was very dosey. because blood was going fast out of my body.i loved staying in the bunks but tidying them up was adifferent story
awesome stories
M1 Camp Recount
We got there in the vans and when we got there got our staff and went up the hill,
tramping up the hill is where hared,
I got skak in a tree,
tents are hard to put up,
I loved sleep in my own bed,
in own house instead of a tent,
sleep in the tent and when I woke up I had sun skream muska on my face,
we got up we went down the hill one time again, before we went and sowe 6 little kea’s,
when we got down we went to the vans to the lag,
when we got there we got a little nap,
In my own bed,
with my friends ,
propyl sleep night,
cabin beds soooo soft
,
bedrolls not so soft than I thot,
cabin showers has cold waters,
see a thing at night,
can not sleep at all but sleep at the end
but it is not so bad.
By A.J.
and iain
when i cracked my funny bone
when i went to the church hall i was playing on bars and jumping over them when that meeting to finish i was going to jump over the bar to go to the car and then.SMACK! i was lying on the ground in lots of pain it really hurt.Mum and dad were there looking at me and said i bet if you didnt tell us to watch you jump over the bar it wouldnt of fail to lift me.then in the night i fell out of bed and it hurt.!!!!.
when i went to australia
when we got to australia it was 5:30 pm we left at 4:08am and we were all tired
but we had to be at check in at 8:00 am so we had hours to spend we were all looking forword
to getting to australia in one piece so when we got on the plane i brought an jet star i pad
i started to play NOVA it was an awesome game i loved i played that for an hour and a half
and then for the next 2 and a half hours i watched the hobbit the desolation of smaug
it was awesome
camp my recount
my favorite thing about camp was when we saw the so called monster.It was so funny when the morning came. Because all the boys were trying to figure it out and me and kian were laughing and laughing it was so funny.BUT when they saw the so called monster i was a bit scared it was scary at first.Then me and kian went to the toliet and laughed and laughed.
Ozone is very rare in our atmosphere, averaging about three molecules of ozone for every 10 million air molecules. In spite of this small amount, ozone plays a vital role in the atmosphere. In the information below, we present "the basics" about this important component of the Earth's atmosphere.
__Click here for larger image__
Ozone is mainly found in two regions of the Earth's atmosphere. Most ozone (about 90%) resides in a layer that begins between 6 and 10 miles (10 and 17 kilometers) above the Earth's surface and extends up to about 30 miles (50 kilometers). This region of the atmosphere is called the stratosphere. The ozone in this region is commonly known as the ozone layer. The remaining ozone is in the lower region of the atmosphere, which is commonly called the troposphere. The figure (above) shows an example of how ozone is distributed in the atmosphere.
What roles does ozone play in the atmosphere and how are humans affected?
The ozone molecules in the upper atmosphere (stratosphere) and the lower atmosphere (troposphere) are chemically identical, because they all consist of three oxygen atoms and have the chemical formula O3. However, they have very different roles in the atmosphere and very different effects on humans and other living beings. Stratospheric ozone (sometimes referred to as "good ozone") plays a beneficial role by absorbing most of the biologically damaging ultraviolet sunlight (called UV-B), allowing only a small amount to reach the Earth's surface. The absorption of ultraviolet radiation by ozone creates a source of heat, which actually forms the stratosphere itself (a region in which the temperature rises as one goes to higher altitudes). Ozone thus plays a key role in the temperature structure of the Earth's atmosphere. Without the filtering action of the ozone layer, more of the Sun's UV-B radiation would penetrate the atmosphere and would reach the Earth's surface. Many experimental studies of plants and animals and clinical studies of humans have shown the harmful effects of excessive exposure to UV-B radiation.
At the Earth's surface, ozone comes into direct contact with life-forms and displays its destructive side (hence, it is often called "bad ozone"). Because ozone reacts strongly with other molecules, high levels of ozone are toxic to living systems. Several studies have documented the harmful effects of ozone on crop production, forest growth, and human health. The substantial negative effects of surface-level tropospheric ozone from this direct toxicity contrast with the benefits of the additional filtering of UV-B radiation that it provides.
What are the environmental issues associated with ozone?
The dual role of ozone leads to two separate environmental issues. There is concern about increases in ozone in the troposphere. Near-surface ozone is a key component of photochemical "smog," a familiar problem in the atmosphere of many cities around the world. Higher amounts of surface-level ozone are increasingly being observed in rural areas as well.
There is also widespread scientific and public interest and concern about losses of ozone in the stratosphere. Ground-based and satellite instruments have measured decreases in the amount of stratospheric ozone in our atmosphere. Over some parts of Antarctica, up to 60% of the total overhead amount of ozone (known as the column ozone) is depleted during Antarctic spring (September-November). This phenomenon is known as the Antarctic ozone hole. In the Arctic polar regions, similar processes occur that have also led to significant chemical depletion of the column ozone during late winter and spring in 7 out of the last 11 years. The ozone loss from January through late March has been typically 20-25%, and shorter-period losses have been higher, depending on the meteorological conditions encountered in the Arctic stratosphere. Smaller, but still significant, stratospheric decreases have been seen at other, more-populated regions of the Earth. Increases in surface UV-B radiation have been observed in association with local decreases in stratospheric ozone, from both ground-based and satellite-borne instruments.
What human activities affect upper-atmospheric ozone (the stratospheric ozone layer)?
The scientific evidence, accumulated over more than two decades of study by the international research community, has shown that human-produced chemicals are responsible for the observed depletions of the ozone layer. The ozone-depleting compounds contain various combinations of the chemical elements chlorine, fluorine, bromine, carbon, and hydrogen and are often described by the general term halocarbons. The compounds that contain only chlorine, fluorine, and carbon are called chlorofluorocarbons, usually abbreviated as CFCs. CFCs, carbon tetrachloride, and methyl chloroform are important human-produced ozone-depleting gases that have been used in many applications including refrigeration, air conditioning, foam blowing, cleaning of electronics components, and as solvents. Another important group of human-produced halocarbons is the halons, which contain carbon, bromine, fluorine, and (in some cases) chlorine and have been mainly used as fire extinguishants.
What actions have been taken to protect the ozone layer?
Through an international agreement known as the Montreal Protocol on Substances that Deplete the Ozone Layer, governments have decided to eventually discontinue production of CFCs, halons, carbon tetrachloride, and methyl chloroform (except for a few special uses), and industry has developed more "ozone-friendly" substitutes. All other things being equal, and with adherence to the international agreements, the ozone layer is expected to recover over the next 50 years or so.
* Text and figure are adapted from the Introduction to "Frequently Asked Questions" of the World Meteorological Organization/United Nations Environment Programme report, Scientific Assessment of Ozone Depletion: 1998 (WMO Global Ozone Research and Monitoring Project-Report No. 44, Geneva, 1999).